Air blown fiber (ABF) tube cables installed in harsh weather environments, such as aerial outside plant cables, are subjected to extreme temperature and environmental conditions. Low temperature shrinkage will ordinarily occur in the longitudinal axis direction of the tube and cable due to the relatively high coefficient of thermal expansion characteristic of the plastic used to manufacture conventional air blown fiber (ABF) tubes and cables. Significant shrinkage in the longitudinal axis direction of air blown fiber tubes may cause induced signal attenuation due to bending of the optical fibers housed in the tubes of the air blown fiber (ABF) tube cable. The optical fibers have a significantly lower coefficient of thermal expansion than the air blown fiber (ABF) tubes in which they reside. Due to their small size, optical fibers have a relatively low buckling resistance resulting in bending of the optical fibers within the air-blown fiber (ABF) tubes which may cause optical transmission signal loss.
Thus, it can be appreciated that the coefficient of thermal expansion and post-extrusion shrinkage can have detrimental effects on the performance of air blown fiber (ABF) tubes used for telecommunications. From a theoretical standpoint, the coefficient of thermal expansion and post-extrusion shrinkage of the tube should be as close to zero as possible. If the coefficient of thermal expansion and post-extrusion shrinkage of air blown fiber (ABF) tubes are not minimized through design and manufacturing, the tubes will shrink during use due to fluctuations in the temperature to which the tubes are exposed and the shrinkage can result in the aforementioned undesirable and sometimes catastrophic signal loss.
Applicants have developed a novel low shrink air blown fiber (ABF) tube that serves to overcome many of the referenced deficiencies of known air blown fiber (ABF) tubes and that provides reduced post extrusion shrinkage and coefficient of thermal expansion compared with previous tubes due to its novel construction and performance features.